1. Technical Field
The present invention relates to a magnetic device that is provided with a magnetic sensor.
2. Background Art
In recent years, in order to cut costs and reduce chip components, devices have been proposed in which induction elements such as magnetic impedance elements are integrated on substrates such as semiconductors. When magnetic impedance elements of this type are used for a magnetic sensor, it is necessary to apply a bias magnetic field to the magnetic impedance elements due to the characteristics of impedance change.
A method that may be considered in order to apply a bias magnetic field to the magnetic impedance elements is, for example, to place magnets adjacent to the magnetic impedance elements (See Japanese Patent Application Laid-Open (JP-A) No. 2002-43649). However, applying a bias magnetic field by means of magnets in this manner poses various problems when applied to magnetic sensors as the magnetic field strength of the individual magnets is not uniform, and it is difficult to consistently apply a bias magnetic field having a constant value.
In contrast, a method of consistently applying a bias magnetic field having a uniform strength to magnetic impedance elements is known in which a spiral-shape or coil-shape conductive layer is formed adjacent to the magnetic impedance elements, and a bias magnetic field is generated by energizing this conductive layer (Japanese Patent Application Laid-Open (JP-A) No. 2001-221838). Because a magnetic sensor in which magnetic impedance elements are arranged along a coil center axis of a conductive layer formed in a coil shape, in particular, has the characteristic that it is possible to apply a strong bias magnetic field consistently to the magnetic impedance elements, this method is preferable as it enables highly accurate magnetic sensors to be obtained.
However, in order to apply a bias magnetic field to the magnetic impedance elements, when a coil-shape magnetic field application device is formed around the impedance elements so as to envelop the magnetic impedance elements, the outer configuration of the overall magnetic device is enlarged by this coil, so that the problem has arisen that this has prevented any size reduction or slenderization of any instrument in which this magnetic device is mounted.